A Century of Gravity

Category Archives: Cool Stuff

In this video, Günther Hasinger, ESA Director of Science, reflects on this historic measurement that inaugurated a century of exciting experiments, investigating gravity on Earth and in space and proving general relativity in ever greater detail. — NASA

NASA: Citizen scientists assemble! NASA’s OSIRIS-REx mission to the asteroid Bennu needs extra pairs of eyes to help choose its sample collection site on the asteroid – and to look for anything else that might be scientifically interesting.

The OSIRIS-REx spacecraft has been at Bennu since Dec. 3, 2018, mapping the asteroid in detail, while the mission team searches for a sample collection site that is safe, conducive to sample collection and worthy of closer study. One of the biggest challenges of this effort, which the team discovered after arriving at the asteroid five months ago, is that Bennu has an extremely rocky surface and each boulder presents a danger to the spacecraft’s safety. To expedite the sample selection process, the team is asking citizen scientist volunteers to develop a hazard map by counting boulders.

“For the safety of the spacecraft, the mission team needs a comprehensive catalog of all the boulders near the potential sample collection sites, and I invite members of the public to assist the OSIRIS-REx mission team in accomplishing this essential task,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson.

For this effort, NASA is partnering with CosmoQuest, a project run out of the Planetary Science Institute that supports citizen science initiatives. Volunteers will perform the same tasks that planetary scientists do – measuring Bennu’s boulders and mapping its rocks and craters – through the use of a simple web interface. They will also mark other scientifically interesting features on the asteroid for further investigation.

The boulder mapping work involves a high degree of precision, but it is not difficult. The CosmoQuest mapping app requires a computer with a larger screen and a mouse or trackpad capable of making precise marks. To help volunteers get started, the CosmoQuest team provides an interactive tutorial, as well as additional user assistance through a Discord community and livestreaming sessions on Twitch.

“We are very pleased and excited to make OSIRIS-REx images available for this important citizen science endeavor,” said Rich Burns, OSIRIS-REx project manager at NASA Goddard Space Flight Center. “Bennu has surprised us with an abundance of boulders. We ask for citizen scientists’ help to evaluate this rugged terrain so that we can keep our spacecraft safe during sample collection operations.”

Sample return isn’t new for NASA – this year, the agency is celebrating the 50th anniversary of the Apollo missions to the Moon, which allowed astronauts to bring back 842 pounds (382 kilograms) of rocks and lunar soil. Those samples helped scientists discover that the Moon has water locked in its rocks and even permanently frozen in craters. These findings and others inspired the agency to create the Artemis program to return humans to the Moon by 2024 and start preparing for human exploration on Mars.

“The OSIRIS-REx mission will continue the Apollo legacy by giving scientists precious samples of an asteroid,” said Lori Glaze, director of the Planetary Science Division at NASA Headquarters in Washington. “These samples will help scientists discover the secrets of planetary formation and the origins of our planet Earth.”

The Bennu mapping campaign continues through July 10, when the mission begins the sample site selection process. Once primary and secondary sites are selected, the spacecraft will begin closer reconnaissance to map the two sites to sub-centimeter resolution. The mission’s Touch-and-Go (TAG) sampling maneuver is scheduled for July 2020, and the spacecraft will return to Earth with its cargo in September 2023.

Goddard provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

NASA: A small satellite designed to hunt for new planets beyond the solar system recently looked down at Earth to capture an image of California’s “City of Stars.”

The greater Los Angeles area stands out in these images from ASTERIA, the Arcsecond Space Telescope Enabling Research in Astrophysics, a satellite not much larger than a briefcase. ASTERIA is a CubeSat, or a small satellite composed of cubic units that measure 10 centimeters (4.5 inches) on each side. This particular CubeSat is made up of six units.

The images, taken March 29, reveal a massive grid of illuminated city streets and freeways. A bright spot near the center of the first image marks the location of Dodger Stadium. (The Dodgers played the Arizona Diamondbacks at home that night.) To the northeast, near the darkness of the San Gabriel Mountains, is NASA’s Jet Propulsion Laboratory in Pasadena, California, which built and operates ASTERIA, and the nearby Rose Bowl Stadium. The close-cropped image shows a region of about 43.5 square miles (70 square kilometers), with a resolution of about 100 feet (30 meters) per pixel.

Lots of orbiting small satellites can take higher-quality pictures of Earth than this one. But ASTERIA is the only CubeSat in orbit that can also look for exoplanets, or planets orbiting stars other than our Sun. Its primary mission objective was to demonstrate precision-pointing technology in a small satellite.

ASTERIA was developed under the Phaeton Program at JPL. Phaeton provided early-career hires, under the guidance of experienced mentors, with the challenges of a flight project. The mission is a collaboration with the Massachusetts Institute of Technology (MIT) in Cambridge. Sara Seager, a professor of planetary science and physics at MIT, is the mission’s principal investigator.

The Mars lander InSight captured this Martian sunset. According to NASA the InSight lander used the Instrument Deployment Camera (IDC) on the end of its robotic arm to image this sunset on Mars on April 25, 2019, the 145th Martian day, or sol, of the mission. This was taken around 6:30 p.m. Mars local time.

I look at the images here and think about what a great science fair project for some enterprising student.

NASA’s caption: Included here are the “raw” versions of the image (above) and the color-corrected version below; it’s easier to see some details in the raw version, but the latter more accurately shows the image as the human eye would see it.

NASA’s Jet Propulsion Laboratory manages InSight for the agency’s Science Mission Directorate. InSight is part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.

A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.

The Moon does have miniscule traces of water (H2O), but apparently enough water to lose, I will let NASA explain:

Researchers from NASA and the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, report that streams of meteoroids striking the Moon infuse the thin lunar atmosphere with a short-lived water vapor.

The findings will help scientists understand the history of lunar water — a potential resource for sustaining long term operations on the Moon and human exploration of deep space. Models had predicted that meteoroid impacts could release water from the Moon as a vapor, but scientists hadn’t yet observed the phenomenon.

Now, the team has found dozens of these events in data collected by NASA’s Lunar Atmosphere and Dust Environment Explorer. LADEE was a robotic mission that orbited the Moon to gather detailed information about the structure and composition of the thin lunar atmosphere, and determine whether dust is lofted into the lunar sky

“We traced most of these events to known meteoroid streams, but the really surprising part is that we also found evidence of four meteoroid streams that were previously undiscovered,” said Mehdi Benna of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland Baltimore County. Benna is the lead author of the study, published in Nature Geosciences.

The newly identified meteoroid streams, observed by LADEE, occurred on Jan. 9, April 2, April 5 and April 9, 2014.

There’s evidence that the Moon has water (H2O) and hydroxyl (OH), a more reactive relative of H2O. But debates continue about the origins of the water, whether it is widely distributed and how much might be present.

“The Moon doesn’t have significant amounts of H2O or OH in its atmosphere most of the time,” said Richard Elphic, the LADEE project scientist at NASA’s Ames Research Center in California’s Silicon Valley. “But when the Moon passed through one of these meteoroid streams, enough vapor was ejected for us to detect it. And then, when the event was over, the H2O or OH went away.”

Lunar scientists often use the term “water” to refer to both H2O and OH. Figuring out how much H2O and how much OH are present is something future Moon missions might address.

LADEE, which was built and managed by NASA’s Ames Research Center in California’s Silicon Valley, detected the vapor using its Neutral Mass Spectrometer, an instrument built by Goddard. The mission orbited the Moon from October 2013 to April 2014 and gathered detailed information about the structure and composition of the lunar atmosphere, or more correctly, the “exosphere” – a faint envelope of gases around the Moon.

To release water, the meteoroids had to penetrate at least 3 inches (8 centimeters) below the surface. Underneath this bone-dry top layer lies a thin transition layer, then a hydrated layer, where water molecules likely stick to bits of soil and rock, called regolith.

From the measurements of water in the exosphere, the researchers calculated that the hydrated layer has a water concentration of about 200 to 500 parts per million, or about 0.02 to 0.05 percent by weight. This concentration is much drier than the driest terrestrial soil, and is consistent with earlier studies. It is so dry that one would need to process more than a metric ton of regolith in order to collect 16 ounces of water.

Because the material on the lunar surface is fluffy, even a meteoroid that’s a fraction of an inch (5 millimeters) across can penetrate far enough to release a puff of vapor. With each impact, a small shock wave fans out and ejects water from the surrounding area.

When a stream of meteoroids rains down on the lunar surface, the liberated water will enter the exosphere and spread through it. About two-thirds of that vapor escapes into space, but about one-third lands back on the surface of the Moon.

These findings could help explain the deposits of ice in cold traps in the dark reaches of craters near the poles. Most of the known water on the Moon is located in cold traps, where temperatures are so low that water vapor and other volatiles that encounter the surface will remain stable for a very long time, perhaps up to several billion years. Meteoroid strikes can transport water both into and out of cold traps.

The team ruled out the possibility that all of the water detected came from the meteoroids themselves.

“We know that some of the water must be coming from the Moon, because the mass of water being released is greater than the water mass within the meteoroids coming in,” said the second author of the paper, Dana Hurley of the Johns Hopkins University Applied Physics Laboratory.

The analysis indicates that meteoroid impacts release water faster than it can be produced from reactions that occur when the solar wind hits the lunar surface.

“The water being lost is likely ancient, either dating back to the formation of the Moon or deposited early in its history,” said Benna.

NASA is leading a sustainable return to the Moon with commercial and international partners to expand human presence in space and bring back new knowledge and opportunities.

There are plenty of videos about the black hole image out there. One in particular predated the press release and I really never got a chance to watch it beforehand.

This morning as I was watching my usual fare, it turns out the video was recommended by Walter Lewin of MIT physic class fame. Check out his channel here. Well if he says it’s good who am I to argue and look over five-million views.

Here’s more on the supermassive black hole at the center of M-87 after that excellent announcement earlier this week. Thanks to NASA / Elizabeth Landau.

Image: NASA/CXC/Villanova University/J. Neilsen

NASA: A black hole and its shadow have been captured in an image for the first time, a historic feat by an international network of radio telescopes called the Event Horizon Telescope (EHT). EHT is an international collaboration whose support in the U.S. includes the National Science Foundation.

A black hole is an extremely dense object from which no light can escape. Anything that comes within a black hole’s “event horizon,” its point of no return, will be consumed, never to re-emerge, because of the black hole’s unimaginably strong gravity. By its very nature, a black hole cannot be seen, but the hot disk of material that encircles it shines bright. Against a bright backdrop, such as this disk, a black hole appears to cast a shadow.

The stunning new image shows the shadow of the supermassive black hole in the center of Messier 87 (M87), an elliptical galaxy some 55 million light-years from Earth. This black hole is 6.5 billion times the mass of the Sun. Catching its shadow involved eight ground-based radio telescopes around the globe, operating together as if they were one telescope the size of our entire planet.

“This is an amazing accomplishment by the EHT team,” said Paul Hertz, director of the astrophysics division at NASA Headquarters in Washington. “Years ago, we thought we would have to build a very large space telescope to image a black hole. By getting radio telescopes around the world to work in concert like one instrument, the EHT team achieved this, decades ahead of time.”

NASA: Astronomers found a pulsar hurtling through space at nearly 2.5 million miles an hour — so fast it could travel the distance between Earth and the Moon in just 6 minutes. The discovery was made using NASA’s Fermi Gamma-ray Space Telescope and the National Science Foundation’s Karl G. Jansky Very Large Array(VLA).

“Thanks to its narrow dart-like tail and a fortuitous viewing angle, we can trace this pulsar straight back to its birthplace,” said Frank Schinzel, a scientist at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. “Further study of this object will help us better understand how these explosions are able to ‘kick’ neutron stars to such high speed.”

Schinzel, together with his colleagues Matthew Kerr at the U.S. Naval Research Laboratory in Washington, and NRAO scientists Dale Frail, Urvashi Rau and Sanjay Bhatnagar presented the discovery at the High Energy Astrophysics Division meeting of the American Astronomical Society in Monterey, California. A paper describing the team’s results has been submitted for publication in a future edition of The Astrophysical Journal Letters.

Pulsar J0002 was discovered in 2017 by a citizen-science project called Einstein@Home, which uses time on the computers of volunteers to process Fermi gamma-ray data. Thanks to computer processing time collectively exceeding 10,000 years, the project has identified 23 gamma-ray pulsars to date.

Located about 6,500 light-years away in the constellation Cassiopeia, J0002 spins 8.7 times a second, producing a pulse of gamma rays with each rotation.

The pulsar lies about 53 light-years from the center of a supernova remnant called CTB 1. Its rapid motion through interstellar gas results in shock waves that produce the tail of magnetic energy and accelerated particles detected at radio wavelengths using the VLA. The tail extends 13 light-years and clearly points back to the center of CTB 1.

Using Fermi data and a technique called pulsar timing, the team was able to measure how quickly and in what direction the pulsar is moving across our line of sight.

“The longer the data set, the more powerful the pulsar timing technique is,” said Kerr. “Fermi’s lovely 10-year data set is essentially what made this measurement possible.”

The result supports the idea that the pulsar was kicked into high speed by the supernova responsible for CTB 1, which occurred about 10,000 years ago.

J0002 is speeding through space five times faster than the average pulsar, and faster than 99 percent of those with measured speeds. It will eventually escape our galaxy.

At first, the supernova’s expanding debris would have moved outward faster than J0002, but over thousands of years the shell’s interaction with interstellar gas produced a drag that gradually slowed this motion. Meanwhile, the pulsar, behaving more like a cannonball, steadily raced through the remnant, escaping it about 5,000 years after the explosion.

Exactly how the pulsar was accelerated to such high speed during the supernova explosion remains unclear, and further study of J0002 will help shed light on the process. One possible mechanism involves instabilities in the collapsing star forming a region of dense, slow-moving matter that survives long enough to serve as a “gravitational tugboat,” accelerating the nascent neutron star toward it.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

The Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Fermi was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.